Exercise 1: Investigation of the Testes and Ovary
- Why are the testes located outside of the body in the scrotum?
The testes work best at temperature lower than the body temperatures. Therefore, process of spermatogenesis takes place optimally at temperatures slightly less than that of the body and hence the testes are located outside in the scrotum.
- What process occurs in the seminiferous tubules?
The seminiferous tubules form the site for germination, maturation, and transportation of the sperm cells within the testes of the male animals. The processes are called spermatogenesis. The process of meiosis takes place within the seminiferous tubules. The sertoli cells found in the lining of the seminiferous tube undergo the process of differentiation converting them into sperms. The sperms are stored in the same tubule until ready for ejaculation.
- Why do sperm and egg go through meiosis?
The sperm and egg undergo meiosis to change them from the diploid state to the haploid state. The sperm and the egg develop two sets of chromosomes that divide half way and unite to form a single set of chromosome that is haploid. This is the process of meiosis.
Inside the ovary, the following follicles are found, the primordial/secondary or primary follicles, mature vesicular follicles, rupturing, corpus albicans, and mature corpus luteum
- How is the endocrine system involved in reproduction?
The endocrine system controls the functions of the reproduction system. The gonads secrete hormones that are responsible for the development of reproduction system. These hormones are the ones responsible for development of secondary sexual characteristics that influences the reproduction system profoundly.
F. What hormones lead to the maturation of both sperm and egg?
The hormones responsible for the maturation of the egg and the sperm include, the GnHR (gonadotropin-releasing hormone) that is secreted in the hypothalamus. The GnHR triggers the release of LH (Leutenizing hormone) and FSH (Follicle stimulating hormone) from the pituitary gland. Therefore, the GnHR, LH, and FSH are responsible for the maturation of the egg and the sperm.
Exercise 2: Reproductive Structures of the Fetal Pig
- Why are some reproductive structures hard to find in the fetal pig?
The reproductive system in fetal pigs exists in the abdominal cavity. This makes it difficult to locate the reproductive structures.
- How does the anatomical arrangement of the organs in the pig compare to that of a human?
The pig and the humans have similarities in their anatomy. Both have placentas implying that nourishment of the fetus in both is through the umbilical code. The pig and humans are omnivorous animals with similar digestive system and the skin. The heart is in a similar location, the gaseous exchange pores are also similar.
C. Explain the differences you saw in the pig versus a human relative to the following organs and structures (if you had a female pig, do only the female structures)
- Uterine tubes and oviducts: the pig are bicornate while the humans have a simplex uterus. The pig has extra two horns that are mistaken for fallopian tubes. The horns are found where the uterine tubes and the uterus meet. It is at his junction where the fetus develops. The horns allow for larger growth of the piglets. Humans have fallopian tubes where the eggs pass through to the uterus.
- Urethral and vaginal openings in the female:
The pig’s urethra and the vagina have a single opening outside the body. The humans have different openings.
The ovaries are located at the extreme ends of the fallopian tubes. The fallopian tube connects the ovary to the uterus in humans but it connects to the uterine hone in pigs.
- How is the pig uterus modified to carry several fetuses?
The uterus of a pig is adapted to carry several fetuses by being large and with uterine horns that give more space.
Exercise 3: Pregnancy and Human Development
- When does fertilization occur? Fertilization occurs when two gametes fuse to form a zygote. This process takes pales in the uterine walls.
- At what point does an embryo turn into a fetus? Describe what a baby looks like at this stage of development.
After fertilization, a zygote is formed that changes to embryo. The embryo changes into fetus after eight weeks since conception. At this stage the unborn has the basic characteristics of a young mammal (child) i.e. has limbs and some of the internal organs in their basic form.
- At what point is the brain fully developed? Describe the activities this allows the baby to do?
The brain of the child is fully developed during the second trimester (13 -16 weeks). During this time, the baby can suck and swallow and make irregular breathing sounds. The fetus has almost a transparent skin. It can feel pain. The muscle tissue is lengthening and bones harden. The eyelashes and brows appear. The baby can make basic active movements as kicking and somersaults.
- What is “quickening”? What is Lanugo? Give a possible function for Lanugo? When do these two phenomena occur?
Quickening refer to the period when the mother begins to perceive the fetal movement in the uterus. Lanugo refers to the fine, soft hair, usually not pigmented found on the body of a fetus. Lanugo occurs between the 7th and the 8th month during pregnancy (( Moore, Keith L (Dec 19, 2011)) .
- Why is the 28th week a crucial point in the development of the fetus?
During the 28th week, the fetus has fully developed lungs that begin to produce surfactant required for breathing. The nostrils also open and the retina begins to fro. The child can open the eyes. The brain begins to develop rapidly.
- Describe some of the physiological events that occur in a baby’s body as it is born and leaves the womb behind.
The baby undergoes the following physiological adaptions soon after birth. The blood circulations, the baby had a different blood circulation that is not entirely similar to that of babies outside the uterus. Therefore, the intrauterine blood circulation changes to one similar to adults. In the uterus, the child’s blood circulation bypasses their lungs. This stops when the child is born and the child begins to breathe independently, i.e. absorb oxygen from the environment into the lungs and exhales it.
Conclusion
The removal of the testes or the ovaries has various effects on the individuals. These effects vary from psychological to medical and hormonal effects. When the testes are removed before the onset of puberty, the individual retains high voice, small genitals, non-muscular build due to lack of the hormones associated with the testes. The individual may grow taller than normal since the estrogen produced through aromatization of testosterone stops bones from growing long. The person may not grow pubic hair and may have no sex drive or very little. The person is also medically sterile. This results since the person cannot from sperms due to the absence of the testes.
Women who have the ovaries removed do not produce estrogen and progesterone. They therefore, attain medical menopause indicating their incapability to get children. The women like men suffer from low libido, vaginal dryness, and difficulty in arousal. Therefore, it can be concluded that the removal of the ovaries significantly impairs sexuality in women (Castelo-Branco, C., Palacios, S., Combalia, J., Ferrer, M. and Traveria, G., 2009).
References
Moore, Keith L (Dec 19, 2011). The Developing Human: Clinically Oriented Embryology . Elsevier
Castelo-Branco, C.; Palacios, S.; Combalia, J.; Ferrer, M. and Traveria, G. (2009). "Risk of hypoactive sexual desire disorder and associated factors in a cohort of oophorectomized women". Climacteric 12 (6): 525–532.
