Human Reproduction Test 12

Morula is a developmental stage between the zygote and blastocyst. It consists of 16-32 cells.

Eye, pigment cells, and heart arise from the mesoderm.

The cervix communicates above with the body of the uterus by an aperture, the internal os and with the vagina below by an opening, the external os.

Mammary glands are milk-producing glands and are characteristic of all female mammals. Mammary glands are derived from a modification of sweat glands. They first appear in embryonic life as clumps of cells proliferating from a longitudinal ridge of ectoderm. Thus, the correct answer is option c, 'Sweat glands'.

The filling up of the sinuses of the penis with blood from the arteries is known as vasocongestion. This builds up the hydraulic pressure in the penis leading to the erection of the penis.

If the oocyte is not fertilized, the corpus luteum degenerates in 10-12 days after ovulation and forms the corpus luteum of menstruation, and is eventually transformed into a white scar, the corpus Albicans.

A lactating mother produces about 1-2 litres of milk per day.

The entry of the sperm in the ovum stimulates the egg to resume and complete its suspended meiosis-II division, thus forming a mature egg cell.

ICSH is secreted by the anterior pituitary.

The inability of a male to achieve or hold onto an erection for complete copulation is known as impotence. Sterility is the inability of the male sperm to fertilise the ovum. Prostatic hypertrophy or prostatomegaly is the enlargement of the prostate gland.

The characteristic structural unit of the Graafian follicle is the antrum.

The secondary oocyte is formed by the meiotic division of primary oocyte (2n), therefore, it is haploid. Primary spermatocyte is formed by the mitotic division of spermatogonium (2n), therefore it is diploid.

Cowper's gland or Bulbourethral gland is found in males responsible for lubrication of the penis. It is homologous to Bartholin gland found in females. The perineal gland is found near the anus responsible for odorous substance. The prostate gland is found in males which makes the semen alkaline in nature to neutralize the acidity of the vagina.

Sperms depend on the catabolism of fructose for their energy demand. At a temperature of zero degree Celsius, the process of respiration stops because respiration is an enzymatic process. This will temporarily inactivate the sperms. 

Rete testis, epididymis, and vasa efferentia are the parts of male reproductive system. Isthmus of uterus is a part of the female reproductive system.

Spermatozoa once released into the female reproductive tract can survive for about 1-3 days.

The external sphincter of the urethra shows the presence of striated muscle fibres around its membranous part, while the internal sphincter shows the presence of smooth muscle fibres at its beginning.

Vigorous contraction of the uterus at the end of pregnancy causes parturition. Parturition is induced by a complex neuroendocrine mechanism. The signals for parturition originate from the fully developed fetus and the placenta which induce mild uterine contractions called fetal ejection reflex. This triggers a release of oxytocin from the maternal pituitary. Oxytocin acts on the uterine muscle and causes stronger uterine contractions, which in turn stimulates the further secretion of oxytocin. The stimulatory reflex between the uterine contraction and oxytocin secretion continues resulting in stronger and stronger contractions. 

Ectoderm forms the lining of gut, gastric and intestinal glands, tongue epithelium, liver, pancreas etc. Endoderm gives rise to epidermis of skin, nasal epithelium, lacrimal glands, salivary glands, enamel of teeth etc.

The body of a mature sperm can be divided into head, neck, middle piece and tail. Middle piece is a portion of sperm, where the axial filament is covered by the helicular structure of mitochondria. A cross section at the mid-point of the middle piece of a sperm will show mitochondria centriote and 9 + 2 arrangement of microtubules.