In the frog antibodies to can block germ cell migration LH r

In the frog. antibodies to can block germ cell migration LH receptors FSH receptors Fibronectin Type collagen All of these responses None of these responses Gonocytes in humans are derivitives of Placenta Chorion Yolk Sac Allantois In a sperm cell ATP hydrolysis in concentrated in the Midpiece Tail Nucleus Acrosome In humans ovulation takes place when blood levels of specific hormones peak? In addition to ovulation, which event is also stimulated Meiosis(remember pick the best answer) Meiosis 1 Meiosis 2 Mitosis 1 Fertilization

Solution

20. Fibronectin.

PGC adhesion and migration can be inhibited if the mesentery is treated with antibodies against Xenopus fibronectin. Thus, the pathway for germ cell migration in these frogs appears to be composed of an oriented fibronectin-containing extracellular matrix. The fibrils over which the PGCs travel lose this polarity soon after migration has ended.

21. Yolk sac .

In the third week, the primordial germ cells migrate in an amoeboid manner - from the primary ectoderm into the yolk sac wall and collect near the exit of the allantois. The primordial germ cells are now extraembryonal, lying in the endoderm and mesoderm of the yolk sac wall.

22. Midpiece.

In sperm mitochondria lie spirally coiledin midpiece. This spirally coiled cloud of mitochondria is called Nebenkern.

23. Meiosis 2.

Whn egg is released from ovary (ovulation), this egg isin the arrested metaphase II stage. Meiosis II resumes only after fertilization.