Complete the following sentences.

(a) In females, the uterine wall thickens to receive the __________.

(b) Endocrine glands release hormones directly into _________for transportation to the __________.

(c) The sex hormones, _________________ and estrogen are responsible for the development of __________ characters.

(d) Release of sex hormones is under the control of a hormone secreted from the __________.

a) Fertilised egg/zygote

The egg gets fertilized with sperm at oviduct to form a zygote. For the proper development of zygote to a full term baby it needs proper nutrients, oxygen etc. which is supplied by blood vessels. Hence uterine lining gets thickened and richly supplied with blood to receive the fertilized egg.

b) Blood stream, the target site

Hormones are produced by endocrine glands which do not have ducts so they secrete hormones and pour directly into the blood stream which is carried to the target organs.

c) Testosterone, secondary sexual

Secondary sexual characters are visible characters which help us to differentiate between two sexes i.e. male and female. The growth of secondary sexual characters is controlled by sex hormones i.e. testosterone in males produced by testes and estrogen in females produced by ovaries.

d) Pituitary gland

The pituitary gland is the master gland which regulates the secretion of hormones from all other endocrine glands.