"During embryonic development red blood cells begin to develop in patches called blood islands. The blood cells secrete growth factors that diffuse only to nearby cells, signaling differentiation into endothelial cells. The endothelial cells eventually form the linings of the blood vessels." The growth factor described in the passage is involved in what type of signaling?a. Autocrine
b. Paracrine
c. Endocrine
d. Juxtacrine

paracrine

Explanation:glands are specialized tissues that secrete specific chemicals substances.these substances may be enzymes,hormones or lubricating fluid.glands secretes their their products through several mechanisms.some involve the use of ducts ,while others do not.

In paracrine secretion,the secretory products reach their target cells by diffusion through the extracellular space or adjacent connective tissue.

Paracrine secretion do not use ducts.

Similar to paracrine is the endocrine ,in which the secretory products goes through the basal lamina ,into the underlying connective tissue and into the vascular syatem.they too do not use ducts