Describe the process of Parturition in humans.
Parturition is the process of childbirth or the delivery of the foetus because of vigorous contraction of uterus at the end of the pregnancy which is after the 9 month gestation period. It is induced by a complex neuroendocrine mechanism. Fully developed foetus gives the signal which induces mild uterine contraction called foetal ejection reflex. This triggers results in release of oxytocin from maternal pituitary. The oxytocin results in stronger contractions of the uterine walls and the secretion of more and more oxytocin. The effect of oxytocin and uterine wall contraction leads to stronger contraction which leads to the expulsion of the foetus through the birth canal or parturition.
When and where do chorionic villi appear in humans? State their function.
Chorionic villi appear on the trophoblast after implantation. Chorionic villi interdigitate with the uterine tissues and jointly forms the placenta which is a structural and functional unit between developing embryo and maternal body.
Draw a sectional view of human ovary and label the different follicular stages, ovum and Corpus luteum.
How is 'oogenesis' markedly different from 'spermatogenesis' with respect to the growth till puberty in the humans?
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Spermatogenesis |
Oogenesis |
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It is the process by which sperms are formed from the sperm mother cell in males. |
It is the process by which ovum is formed from the oogonia in females. |
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After the second meiotic divisions in a single spermatogonium, 4 spermatids are obtained, which undergo maturation to form 4 sperm cells, or spermatozoa |
After the second meiotic divisions in the single oogonium, only one ovum and three polar bodies are obtained. |
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Spermatogenesis occurs in males from puberty to death. |
In females, oogenesis starts before birth and occurs until menopause. |
Mention any three characteristics of Neanderthal man that lived in near east and central Asia.
Characteristics of Neanderthal man
(i) They possess a brain capacity of 1400 cc.
(ii) They were short but very strong with outward curved thigh bones.
(iii) They used hides to protect their body and to bury the dead.
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