The anterior pituitary is the front portion of the pituitary, a small gland in the head called the master gland. Hormones secreted by the anterior pituitary influence growth, sexual development, skin pigmentation, thyroid function, and adrenocortical function. These influences are exerted through the effects of pituitary hormones on other endocrine glands except for growth hormone which acts directly on cells.
There are 6 major hormones produced by the anterior pituitary, which can be grouped according to structure. Luteinizing hormone (LH), follicle stimulating hormone (FSH) and thyroid stimulating hormone (TSH). These are glycoproteins. Growth hormone (GH or HGH) and prolactin. These two hormones belong to a family of polypeptide hormones. They share elements of their structure and differ only by 8 amino acids, GH has 191 amino acids and prolactin has 199. Adrenocorticotrophic hormone (ACTH) is a polypeptide. Melanocyte stimulating hormone (MSH) which has 39 amino acids.