Human Reproduction

After ovulation, several changes continue to occur in the ovaries. The remaining follicular cells undergo structural and biochemical changes. They develop into the corpus luteum, which produce both estrogen and progesterone.

It is in the upper third part of the fallopian tubes, where the process of fertilisation most commonly takes place.

The seminiferous tubules are located in the testes.

Oral contraceptives generally contain progesterone. By maintaining a higher level of progesterone through contraceptives, the signals from the brain to the ovaries initiate the ovarian cycle, which lead to suppression of follicle maturation and ovulation takes place.

The vas deferens is a narrow tube connecting the epididymis, where the sperms are stored to the urethra (the duct that can carry either urine or semen).

During spermatogenesis, the number of chromosomes is halved by meiosis. The primary spermatocytes undergo two meiotic divisions to give rise to spermatids. As a result, mature sperms are haploid. This is also true of a mature ovum, which undergoes meiosis prior to ovulation. A zygote is a fertilized egg.

Tubal ligation consists of cutting out a small piece of the each fallopian duct. The eggs can no longer descend into the uterus and the sperm can no longer reach the egg.

These are elongated and pyramidal cells with their base attached to the basal lamina while its apical end spread into the lumen of the seminiferous tubule.

It is a muscular duct exiting from the scrotum via the inguinal canal into the ejaculatory duct. It helps in the conduction of sperms from the testes to the ejaculatory duct by peristalsis.

The ICSH hormone being released from the anterior pituitary stimulates the interstitial cells to secrete the testosterone.

In the testes, these are the groups of cells called the interstitial cells of Leydig. Their main purpose is to produce the hormone, i.e. testosterone.

It is released by the developing ovarian follicle and corpus luteum. It is associated with the development of sex associated characters such as breast development, axillary and pubic hair, etc.

During the preantral phase, the follicular cells acquire receptors for various hormones. The granulosa cells develop receptors for FSH and estrogen while the thecal cells acquire receptors for LH. Ovulation occurs in response to a sudden rise in plasma LH.

In this phase, the follicles develop further. The FSH stimulates one of the follicles. The stimulated follicle grows in size. This follicle is called the Graafian follicle. This phase lasts from the 6th to the10th day.

Progesterone restricts lactation during pregnancy. The fall in progesterone level following delivery is one of the activates for milk production.

It is defined as a pear-shaped organ, broader on the upper end and narrower on the lower end. The upper end is called the body of the uterus and the lower end is called the cervix. At the upper end, it communicates with the oviducts of either side whereas the cervix connects into the vaginal canal which opens to the outside.

Respiratory rate is normally unchanged during gestation.

During the I meiotic division in oogenesis, a large secondary oocyte is produced. The secondary oocyte will divide to produce an egg and a polar body. The polar bodies, although dysfunctional, contain a full set of chromosomes. Meiosis in females starts at birth and halts in the prophase I, and it does not resume until puberty. The II meiotic division will resume after the penetration of sperm.

It is true as the function of the prostate is to secrete a slightly alkaline, milky fluid, making 20-30% of the volume of the semen along with spermatozoa and seminal vesicle fluid.

It is true that the fetal heart rate is about double that of a healthy adult. By the starting of the 9th week of pregnancy, the normal embryo heart rate is an average of 175 BPM. At this point it begins a rapid decline to the normal embryo heart rate for the middle of the pregnancy of about 120-180 BPM.

The conduction of the intervillous spaces of the placenta with maternal blood allows the conduction of nutrients and oxygen from the mother to the fetus. Nutrient transfer to the developing embryo takes place through both active and passive transport.

It is true that in a neonate, large intrathoracic pressures are generated during the first few breaths.

Fetal blood has a higher hemoglobin content than adult blood and fetal hemoglobin has a higher affinity for O₂ than adult hemoglobin. The O₂ content of blood in the umbilical vein is about 160 ml/l.

The kidneys play an important role in the regulation of acid-base balance of the developing embryo within the mother's womb.

The sex of an individual is determined by a single gene on the Y chromosome. In the absence of a Y chromosome, the development of the gonads will follow the female pattern.