From where the parturition signals arise-mother or foetus? Mention the main hormone involved in parturition.
Parturition is induced by a complex neuroendocrine mechanism. The signals for parturition originate from the fully developed foetus and the placenta which induce mild uterine contractions called foetal ejection reflex.
The hormone involved in parturition is oxytocin that acts on the uterine muscle and causes stronger uterine contractions. This leads to the expulsion of the baby out of the uterus through the birth canal.
What is the significance of epididymis in male fertility?
The epididymis helps the sperm in attaining maturity, acquiring increased motility and fertilising capacity. It also stores sperms for a short period before entering the vasa deferens. The epididymis shows peristatic and segmenting contractions at intervals to push the sperm away from the testis.
Give the names and functions of the hormones involved in the process of spermatogenesis. Write the names of the endocrine glands from where they are released.
$$ \text { Hormones involved in spermatogenesis are } $$
| Hormone | Function | Gland |
|---|---|---|
| Gonadotrophin releasing hormone (GnRH) | Acts on pituitary to secrete LH and FSH. | Hypothalamus |
| Luteinizing Hormone (LH) | Acts on Leydig cells and stimulates synthesis and secretion of androgens | Pituitary |
| Androgens | Stimulate process of spermatogenesis | Testis |
| Follicle Stimulating Hormone (FSH) | Acts ons sertoli cell and stimulates secretion of some factors that help in process of spermiogenesis | Pituitary |
The mother germ cells are transformed into a mature follicle through series of steps. Provide the missing steps in the blank boxes.
The germinal epithelial cells divide repeatedly until many diploid oogonia are formed. The oogonia grow to form primary oocytes. Each primary oocyte then gets surrounded by a layer of granulosa cells and then called the primary follicle. The primary follicles get surrounded by more layers of granulosa cells and called secondary follicles.
The secondary follicle soon transforms into a tertiary follicle which is characterised by a fluid filled cavity called antrum. The primary oocyte within the tertiary follicle undergoes meiotic division to become a secondary oocyte and a first polar body (haploid).
The tertiary follicle further changes into the mature follicle or Graafian follicle. The Graafian follicle now ruptures to release the secondary oocyte (ovum) from the ovary by the process called ovulation.During reproduction, the chromosome number (2n) reduces to half ( $n$ ) in the gametes and again the original number ( $2 n$ ) is restored in the offspring. What are the processes through which these events take place?
The meiotic cell division reducers the chromosome numbers to half during gametogenesis and diploid (2n) number of chromosome is restored by the union of male and female gamete through process of fertilisation.