When cells are veryclose to one another, some of the mol-ecules on the cellsâ plasma membranesmay bind together in specific ways.Many of the important interactionsbetween cells in early developmentoccur by means of direct contact be-tween cell surfaces (figure 7.3 a).ecause these proteins may constituteless than 0.01% of the total mass of protein in a cell, puri-fying them is analogous to searching for a particular grainof sand in a sand dune! However, two recent techniqueshave enabled cell biologists to make rapid progress in thisarea. 7.1 Cells signal one another with chemicals.
The Maenads (pronounced Maynads) were female revelors in the cult of Dionysus. The god's frenzied Thracian worshippers, the Maenads, accompanied Dionysus on his travels crowned with wreaths of ivy, oak or fir and draped in the skins of animals.
A gonad or sex gland or reproductive gland is an endocrine gland that produces the gametes (germ cells) of an organism. In the female of the species the reproductive cells are the egg cells, and in the male the reproductive cells are the sperm. The male gonad, the testicle, produces sperm in the form of spermatozoa.The female gonad, the ovary, produces egg cells. Both of these gametes, are haploid germ cells.n the female of the species the reproductive cells are the egg cells, and in the male the reproductive cells are the sperm. The male gonad, the testicle, produces sperm in the form of spermatozoa. The female gonad, the ovary, produces egg cells. Both of these gametes, are haploid germ cells.