Few problems along with their solutions from this chapter are given follows:

Q. Spermiation is the process of the release of sperms from

(a) seminiferous tubules                                 

(b) vas deferens

(c) epididymis                                                

(d) prostate gland

Ans. (a) seminiferous tubules

The process of release of spermatozoa from Sertoli cells into the cavity of the seminiferous tubules is called spermiation. From here, sperms pass via vasa efferentia into the epididymis for temporary storage.

Q. From where the parturition signals arise: mother or foetus? Mention the main hormone involved in parturition.

Ans. Parturition is induced by a complex neuroendocrine mechanism. The signals for parturition originate from the fully developed foetus and the placenta which induce m Id 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.

Q. A human female experiences two major changes, menarche and menopause during her life. Mention the significance of both the events.

Ans. In human beings, initiation of menstruation at puberty (between age 9-15 years) is called menarche. While, menstrual cycle ceases at around 50 years of age, which is termed as menopause. Menarche signifies the onset of puberty, i.e., beginning of reproductive phase in female.

Menopause signifies the end of reproductive phase in female. At this age supply of healthy eggs is very low, the levels of the hormones secreted by the ovaries decline and the menstruation stops. The uterus no longer remains conductive for foetal growth.

Q. The zygote passes through several developmental stages till implantation. Describe each stage briefly with suitable diagrams.

Ans. The zygote passes through the following stages till implantation:

(a) The zygote divides into two-cell stage called cleavage. This development takes place when the zygote is still in the isthmus.

(b) The cleavage undergoes further rounds of mitosis to form 2, 4, 8 and finally 16-celled stage. These daughter cells are called blastomere.

(c) The embryo with 8-16 blastomeres is called a morula.

(d) The morula continues to divide and transforms into blastocyst as it moves further into uterus.

(e) The blastomeres in the blastocyst are arranged into a surface layer called trophoblast and a cluster of interior cells attached to trophoblast are called the inner cell mass.

(f) The trophoblast layer then gets attached to the endometrium and inner mass cells get differentiated as embryo. (v) After attachment, the uterine cells divide rapidly to cover the blastocyst.

(g) The blastocyst becomes embedded in the uterine endometrium. This is called implantation.