12 Male Development and Mating Behavior

Abstract

I. INTRODUCTION AND OVERVIEW OF MALE ANATOMY
The complexity of the anatomy and mating behavior of Caenorhabditis elegans males poses a variety of interesting questions in neurobiology and developmental biology. The mating structures of the male tail differ in form between nematode species and hence provide an opportunity to study the determinants of morphology and their evolution. The fact that the male is dispensable for laboratory culture makes genetic analysis of the male attractive because strains can be easily maintained as hermaphrodites, and their defective males can be studied. In particular, mutant males are often examined as the progeny of Him (high incidence of males) hermaphrodites (Hodgkin et al. 1979), which segregate XO male progeny by X chromosome nondisjunction during meiosis. We discuss here the major features of male development and behavior and those aspects that have been analyzed most intensively. We begin with an overview of male anatomy, discuss mating behavior, and then discuss the development of each structure. Table 1 summarizes the male-specific neurons, Table 2 summarizes the other cells discussed in this chapter, and Table 3 summarizes the genes discussed in this chapter.

The male anatomy differs from that of the hermaphrodite in that the male has a single-armed somatic gonad of only 55 cells as well as 41 specialized muscles, 79 additional neurons (87 sex-specific; White et al. 1976; Sulston et al. 1980), 36 extra neuronal support cells (socket and sheath cells), 23 proctodeal cells, and 16 hypodermal cells associated with mating structures. Most of these...