Human Reproduction: From Gametes to Birth and Lactation Assignment Sample

Human Reproduction: From Gametes to Birth and Lactation

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Task 1: Poster

a) Structure and function of the three parts of the male and female reproductive system

Male Reproductive System

Penis

This is the main sexual organ of the male. This has three parts, such as the root, the body, and the glans. The root of the penis is connected to the wall of the abdomen (Chung, 2020). The body of the penis looks like a cylinder. The glans of the penis look cone-shaped. The function of the penis is to transport urine and semen from the body.

Testicles

This organ looks like an oval and its size is like large olives. Two tests can be found in the male body (John Hopkins Medicine, 2019). This is responsible for the formation of the sex hormone testosterone. It also forms sperm.

Prostate Gland

This organ looks like a walnut and is seen below the “urinary bladder”. This organ is responsible for the ejaculation of additional fluid (Prostate Cancer Foundation, 2017). This fluid works for the nourishment of the sperm.

Female Reproductive System

Vagina

This is a “muscular canal,” and it can be wider at the time of the delivery of the baby. After that, it went back to its previous positions (Maseroli, and Vignozzi, 2020). It is banded with mucous membranes, which are responsible for maintaining moisture.

Fallopian tubes

It is associated with the upper part of the uterus and are responsible for the travel of the ovum from the ovaries to the uterus (Dulohery et al. 2020). Within this organ, fertilisation of eggs occurs through the sperm.

Ovaries

This is an oval-shaped gland. It can be found within either side of the uterus. It is responsible for the formation of hormones and eggs.

b) Evaluation of Oestrogen, testosterone, and progesterone effects on the reproductive system

Table 1: Evaluation of Oestrogen, testosterone, and progesterone effects on the reproductive system

Hormone	Low amount	High amount
Oestrogen This hormone is the main female hormone, which can be seen in male also (Silva et al. 2021). This hormone leads to the strengthening of the bones and promotes sexual development.	The low amount of this hormone leads to the dryness of the vaginal area and is responsible for irregularities of the periods and problems in sleeping. In men, it leads to the loss of bone and store of fat within the abdominal area.	Leads to fibroids, breast cancer and minor acne. Within men, it leads to “Erectile dysfunction (ED)” and infertility.
Testosterone Higher amounts can be found in males and it can be found in females.	Low amounts lead to depression, and muscle weakness in females (Santos et al. 2020). In men, it leads to the loss of hair, weight gain, and mood swings.	High amounts lead to hair thinning, thyroids, and PCODs in females. In men, it leads to minimization of sex drive, heart problems, and damage to the kidney.
Progesterone This can be found in females at the time of the 2nd phase of the menstruation cycle within the ovary (Cable and Grider, 2020). As a precursor of testosterone, it can be seen in males.	Low level leads to an irregular menstrual cycle in females and enlargement of the prostate in males.	High amounts lead to an increase or decrease in weight in females and an imbalance of hormones in males.

c) Draw

i) The immature ovum matures between 0 and 14 days of the menstrual cycle.

Figure 1: Maturity of an ovum in the menstrual cycle

ii) Development of the egg, supported by corpus lutetium and secreted from these cells at ovulation.

Figure 2: Primary follicle

Figure 3: Graafian follicle

Figure 4: Development of corpus lutetium

iii) The corpus lutetium’s progesterone secretion during post-ovulation and an explanation of the purpose of the menstrual cycle.

Figure 5: Post-ovulation hormonal activities

d) Compare and contrast gametogenesis in males and females

Table 2: Compare and contrast of gametogenesis in males and females

Process	Males	Females
Gametogenesis	This process is known as “spermatogenesis” and produces sperms. This process started from the epithelial cells which are present in the testis. Numerous “spermatogonia” are formed in the germinal epithelium as a consequence of mitosis and ongoing cell division. This process developed within the primary spermatocyte (Martinhago and Furtado, 2022). This process is controlled through the anterior pituitary and the hypothalamus. The hormone secreted by the pituitary is responsible for the secretion of the hormone testosterone. This is responsible for the development of “spermatogonia” for the development of sperm.	This process involves the development of female gametes. This process started within the germ cells which is recognized as “Oogonium”. These are mainly seen within the females before the time of birth (Martinhago and Furtado, 2022). Countless numbers of oogonia are formed at the time of development of the fetus of the female. Two maturation divisions can be found within the primary oocytes such as “Meiosis I” and “Meiosis II”. The hormone progesterone is responsible for the limitations of oogenesis.

Task 2: Flowchart and Summary

a) Pathway of sperm from the male testes to the uterine tube

• Spermatogenesis: In the testes, spermatogenesis occurs to form male gametes (sperms) from spermatogonium through mitosis followed by meiosis I and II. In this process, a diploid germ cell gives rise to four sperms.
• Epididymis: During spermatogenesis, spermatids traverse to the epididymis from the lumen of the testes and further differentiate into sperms. These sperms are stored at the epididymis where the maturation of sperm occurs.
• Vas Deferens: This is the elongation of the epididymis which helps sperm to travel from the epididymis to the ejaculatory ducts.
• Seminal Vesicles: During the transportation of sperms from the epididymis to the ejaculatory ducts, these vesicles provide motility, sperm chromatin stability, and immunity to survive in the female reproductive tract.
• Ejaculatory ducts: These are the combination of vas deferens and seminal vesicle duct. These ducts deliver sperm through the prostrate to the urethra.
• Prostrate: This part secretes fluid that protects sperm by providing nutrition (Murcia Lora, 2021). It generates citrate and a few enzymes that help the female reproductive system's semen clot-breaking system work.
• Urethra: This part further facilitates the flow of semen for ejaculation purposes. This also helps in the flow of urine.
• Penis: This organ helps to ejaculate sperm to the vagina.
• Vagina: This organ produces a passage for the penis to ejaculate sperms and receives sperm to enhance the fertilization process.
• Cervical canal: Sperms travel through the cervix via the cervical canal. Sperms swim toward the fallopian tube through this canal and capacitation occurs at this stage.
• Uterine tube: At this location, sperms reach the ovum and try to fertilize it.
• Fertilization: Finally, one sperm successfully fertilizes the ovum.

b) Pathway of an ovum from the female ovary to implantation in the uterus

• Oogenesis: This process refers to forming a haploid ovum from diploid oogonia through mitosis followed by meiosis I and II. This process occurs in the ovary.
• Ovulation: This process is a part of the menstrual cycle and its function is to release an ovum/egg from the ovary.
• Oviduct/Uterine Tube: This is also known as the fallopian tube. It helps the ovum to reach the uterus. Usually, fertilization between an ovum and a sperm occurs at the ampulla region of this uterine duct.
• Uterus: This is an important organ of the female reproductive system that plays a crucial role in fertility, pregnancy, and menstruation (Acharya, and Das, 2022). Fertilized ovum gets implanted at the uterine wall while the non-fertilized ovum expulses through menstruation.
• Fertilization: This process occurs at the ampulla region of the fallopian tube.
• Implantation: This process involves the attachment of fertilized egg/embryo to the uterus’s endometrial surface. Furthermore, this takes over the epithelium, then enters the mother’s bloodstream to create a placenta.

c) Indicate on both flowcharts where fertilization could occur.

Figure 6: Pathways of sperm and ovum in the process of fertilization

d) Changes must take place in the sperm and ovum to achieve fertilization.

The fertilization process takes place at the ampulla region of the uterine tube where numerous sperms travel across the fallopian tube to reach the ovum during the ovulation stage. At this meeting point, some changes occur in the sperm and ovum which further facilitates fertilization of the ovum. Two significant reactions occur at this stage, viz. acrosomal reaction and cortical reaction.

Changes in the sperm

The sperm experiences an acrosomal reaction before achieving fertilization. The sperm changes in the sperm initiate immediately after its production in the testes. Nucleus condensation and tail elongation occur at the testes and epididymis. The elongated tail plays a crucial role in the transportation of sperm to the fallopian tube through the cervix. The acrosome or the anterior part of the sperm forms during spermiogenesis (Rickard, and de Graaf, 2020). After ejaculation, sperms undergo capacitation that increases their penetration capability to help them reach the ovum. When the sperm reaches the egg, binding occurs at the glycoprotein-rich zona pellucida that surrounds the egg. At this stage, the acrosomal reaction occurs where the hydrolytic enzymes digest the wall of zona pellucida at the point of contact. This further permits the sperm to enter into the ovum to fertilize successfully which further results in the development of a zygote.

Changes in the ovum

The ovum faces major changes before fertilization where the cortical reaction is the most significant. The ovum is initially protected by the glycoprotein-rich layer zona pellucida. This layer protects the ovum from multiple fertilization by sperm around it because biologically, only one sperm can fertilize the ovum. During the acrosomal reaction, the layer of zona pellucida dissolves at the contact point of one sperm and permits it to penetrate the layer to go inside the ovum for fertilization. As soon as fertilization occurs, the cortical reaction takes place at the ovum (Carlisle, and Swanson, 2021). This reaction facilitates the release of the calcium ions that are involved in the hardening process of the zona pellucida. This helps in the prevention of other sperms from entering the ovum. At the same time, meiosis II occurs inside the ovum for the formation of a haploid nucleus that successfully fuses with the haploid nucleus of the sperm to develop a zygote.

e) Embryonic developmental changes up to eight weeks

Number of weeks	Changes
Week 1	Fertilization This stage starts immediately after fertilisation, when the zygote is formed. This zygote further develops blastocyst through several cell divisions. At this stage, the unicellular zygote develops into a multicellular embryo and forms the placenta.
Week 2	Implantation At this stage, implantation of the blastocyst into the wall of the uterus occurs, that forms the bilaminar germ disc. This disc consists of an epiblast that will further develop into an embryo and a hypoblast, which constitutes the yolk sac.
Week 3	Gastrulation The embryo further involves in the gastrulation stage, where the epiblast layer differentiates into ectoderm, mesoderm, and endoderm. This ectoderm develops into nervous systems and skin (Rossant, and Tam, 2022). The mesoderm gives rise to bones, blood vessels, and muscles. The endoderm forms the digestive system, lungs, and other internal organs.
Week 4	Neurulation During this time, neurulation occurs through the formation of the spinal cord and brain from the neural tube. At this stage, activities of the ectoderm layer occur (Xue et al. 2020). Furthermore, the development of the heart and the formation of blood cells initiate in the yolk sac.
Week 5	Organogenesis During this time, the development of organs such as the nose, eyes, facial features, limbs, and ears occurs (Liu, 2020).
Week 6	Organogenesis Development of the nervous system, brain, respiratory, and digestive system.
Week 7	Organogenesis During this time, outer genital organs and umbilical cord formation take place.
Week 8	Organogenesis completion of the significant organ systems takes place along with the development of fingers and toes (Haniffa et al. 2021). The movement of foetuses initiates during this time.

Task 3: Information leaflet for first-time parents

a) The Role of the Placenta

This organ has several functions and the most important function is to give nutrients and oxygen. Another function is to eliminate waste from the developing baby. It works to give protection to the mothers from infections during pregnancy so that antibodies can enter into the fetus with the help of the placenta. It also assures that the baby is capable of getting enough O₂ and it filters out the CO2. “Oxygenated blood” also reaches the fetus with the help of the umbilical vein (Ortega et al. 2022). This is also responsible for the regulations of the blood of the mother and fetus so that both types of blood cannot be mixed with each other.

Two main hormones are produced through this organ and it controls and supports the pregnancy. Oestrogen is produced from this organ which is responsible for the preparations of the breast for lactation so that any issues cannot occur at the time of breastfeeding. Another hormone is progesterone which is responsible for the preparations of the body for labour by permitting the “uterus to contract” (Graham, and Heazell, 2020). This hormone is responsible for the development of this organ and fetus. This organ also works for “thermoregulation” so that the temperature of the developing fetus can remain under control.

b) Hormone Regulation on Birth

Birth cycles are restricted by the staggering impacts of hormones like oxytocin, progesterone, and prostaglandins. Oxytocin, delivered by the mother's pituitary organ, stimulates uterine pressure and cervical widening. Progesterone, which slackens the uterus, diminishes concentration, and work starts. Prostaglandins discharged by uterine and fetal membranes behave like oxytocin, working with uterine contractions. As work advances, these hormonal changes bring about the positive impacts of compressions of the uterus and widening of the cervix, eventually prompting the birth of a child (Kenkel, 2021). Hormonal imbalances and issues can cause difficulties during labour. Accordingly, medical services suppliers ought to audit and control these synthetic compounds for a long time to come.

c) Hormone Regulation on Lactation

Lactation, or the production, and the arrival of milk from the mammary organ, is constrained by hormonal synthetics, including prolactin, oxytocin, and oestrogen. Prolactin, discharged by the pituitary organ, stimulates milk creation in the mammary glands. Oxytocin, additionally emitted by the pituitary organ, prompts the smooth muscle cells that encompass the mammary glands to contract, permitting the milk stream. Oestrogen delivered by the ovaries prepares the mammary organs for milk creation (Ni et al. 2021). The recurrence and power of breastfeeding can likewise influence the creation of these synthetic compounds, with breastfeeding prompting prolactin discharge and expanded milk production. Hormonal uneven characteristics and issues can prompt breastfeeding troubles. Hence, well-being experts genuinely must screen and deal with these synthetics during breastfeeding.

d) Role of hormones in birth and lactation

The hormones that control birth and lactation have some crossover, however, play various parts in each cycle. During birth, oxytocin is the key compound that controls uterine pressure and cervical enlargement. Its arrangement is invigorated by the strain of the child’s head against the cervix and the energy of the areola during taking care. This hormone plays a significant part in the acceptance of birth and delivery (Ramiro-Cortijo et al. 2023). During birth, progesterone levels drop, permitting work to start. It relaxingly affects the uterus, which is fundamental for keeping up with pregnancy, yet restrains the beginning of work.

During breastfeeding, prolactin is the primary hormone that controls milk creation. It is discharged by the pituitary organ and invigorated by the baby's suckling of the breast. Prolactin invigorates milk creation in the mammary glands and assumes a significant part in keeping up with lactation. Work-related oxytocin is additionally associated with lactation. The smooth muscle cells that encompass the mammary gland join and deliver milk. Oestrogen, which prepares the mammary organs for milk creation, likewise plays a part in breastfeeding.

A portion of these hormones plays a part in both birth and lactation, however by and large their jobs are different. Oxytocin assumes a vital part in the two cycles, however, its properties are remarkable (National Childbirth Trust, 2019). Progesterone and estrogen play a minor part in breastfeeding, as opposed to their job in pregnancy and labour. Prolactin is fundamental for milk creation, but not really for parturition. Understanding these hormonal errors is basic for medical care experts to guarantee compelling labour and breastfeeding.

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Reference list

Book

Liu, A. ed., 2020. Animal Models of Human Birth Defects (Vol. 1236). Springer Nature.

Journals

Acharya, D. and Das, D.K., 2022. A novel Human Conception Optimizer for solving optimization problems. Scientific Reports, 12(1), p.21631.

Cable, J.K. and Grider, M.H., 2020. Physiology, Progesterone.

Carlisle, J.A. and Swanson, W.J., 2021. Molecular mechanisms and evolution of fertilization proteins. Journal of Experimental Zoology Part B: Molecular and Developmental Evolution, 336(8), pp.652-665.

Chung, E., 2020. Penile reconstructive surgery in Peyronie disease: challenges in restoring normal penis size, shape, and function. The World Journal of Men's Health, 38(1), pp.1-8.

Dulohery, K., Trottmann, M., Bour, S., Liedl, B., Alba?Alejandre, I., Reese, S., Hughes, B., Stief, C.G. and Kölle, S., 2020. How do elevated levels of testosterone affect the function of the human fallopian tube and fertility?—New insights. Molecular Reproduction and Development, 87(1), pp.30-44.

Graham, N. and Heazell, A.E., 2020. When the fetus goes still and the birth is tragic: the role of the placenta in stillbirths. Obstetrics and Gynecology Clinics, 47(1), pp.183-196.

Haniffa, M., Taylor, D., Linnarsson, S., Aronow, B.J., Bader, G.D., Barker, R.A., Camara, P.G., Camp, J.G., Chédotal, A., Copp, A. and Etchevers, H.C., 2021. A roadmap for the human developmental cell atlas. Nature, 597(7875), pp.196-205.

Kenkel, W., 2021. Birth signalling hormones and the developmental consequences of caesarean delivery. Journal of Neuroendocrinology, 33(1), p.e12912.

Maseroli, E. and Vignozzi, L., 2020. Testosterone and vaginal function. Sexual medicine reviews, 8(3), pp.379-392.

Murcia Lora, J.M., 2021. Assessment & diagnostic test to check free pathways for sperm swimming in the genital tract. Academia Letters, p.2.

Ni, Y., Chen, Q., Cai, J., Xiao, L. and Zhang, J., 2021. Three lactation-related hormones: Regulation of hypothalamus-pituitary axis and function on lactation. Molecular and Cellular Endocrinology, 520, p.111084.

Ortega, M.A., Fraile-Martínez, O., García-Montero, C., Sáez, M.A., Álvarez-Mon, M.A., Torres-Carranza, D., Álvarez-Mon, M., Bujan, J., García-Honduvilla, N., Bravo, C. and Guijarro, L.G., 2022. The pivotal role of the placenta in normal and pathological pregnancies: a focus on preeclampsia, fetal growth restriction, and maternal chronic venous disease. Cells, 11(3), p.568.

Ramiro-Cortijo, D., Singh, P., Herranz Carrillo, G., Gila-Díaz, A., Martín-Cabrejas, M.A., Martin, C.R. and Arribas, S.M., 2023. Association of maternal body composition and diet on breast milk hormones and neonatal growth during the first month of lactation. Frontiers in Endocrinology, 14, p.514.

Rickard, J.P. and de Graaf, S.P., 2020. Sperm surface changes and their consequences for sperm transit through the female reproductive tract. Theriogenology, 150, pp.96-105.

Rossant, J. and Tam, P.P., 2022. Early human embryonic development: blastocyst formation to gastrulation. Developmental cell, 57(2), pp.152-165.

Santos, H.O., Howell, S., Nichols, K. and Teixeira, F.J., 2020. Reviewing the evidence on vitamin D supplementation in the management of testosterone status and its effects on male reproductive system (testis and prostate): mechanistically dazzling but clinically disappointing. Clinical Therapeutics, 42(6), pp.e101-e114.

Silva, L.D.A., de Mello, M.R.B., Oliveira Pião, D.D., Silenciato, L.N., de Quadros, T.C.O., de Souza, A.H. and Barbero, R.P., 2021. Effects of experimental exposure to zearalenone on reproductive system morphometry, plasma oestrogen levels, and oocyte quality of beef heifer. Reproduction in Domestic Animals, 56(5), pp.775-782.

Xue, X., Wang, R.P. and Fu, J., 2020. Modeling of human neurulation using bioengineered pluripotent stem cell culture. Current opinion in biomedical engineering, 13, pp.127-133.