Which one of the following is the most likely reason of not occurring regular menstruation cycle in females?
Fertilisation of the ovum
maintenance of the hypertrophical endometrial lining
Maintenance of high concentration of sex hormones in the blood stream
Maintenance of high concentration of sex hormones in the blood stream
A.
Fertilisation of the ovum
If fertilisation occurs and the foetus is implanted in the endometrium the trophoblast cells of the developing placenta secrete a hormone human chorionic Gonadotrophic (hCG). This hormone-like LH maintains the corpus luteum and the secretion of progesterone and estradiol by it. These two hormones check the breakdown of the endometrium of the uterus. The absence of menstrual bleeding is the earilest sign of pregnancy.
Signal from fully developed foetus and placental ultimately lead to parturition which requires the release of
oestrogen fro placenta
oxytocin from maternal pituitary
oxytocin from foetal pituitary
oxytocin from foetal pituitary
In human female, the blastocyst
forms placenta even before implantation
gets implanted into uterus three days after ovulation
gets nutrition from uterine endometrail secreation only after implantation
gets nutrition from uterine endometrail secreation only after implantation
Secretions from which one of the following are rich in fructose, calcium and some enzymes?
Male accessory glands
Liver
Pancreas
Pancreas
Which one of the following correctly describes the location of some body parts in the earthworm Pheretima?
Two pairs of accessory glands in 16-18 segments
Four pairs of spermathecae in 4-7 segments
One pair of ovaries attached at intersegmental septum of 14th and 15th segments
One pair of ovaries attached at intersegmental septum of 14th and 15th segments
