Circulatory System Muscle and Fat Body

The heart, aorta, musculature, fat body, lining of the hemocoel, and some components of the reproductive system are derived from the somites and median mesoderm formed after gastrulation. As noted earlier, the median mesoderm gives rise to hemocytes. In most embryos, each somite becomes hollow and forms three interconnected chambers, the anterior, posterior, and ventrolateral pouches. The latter grows into the adjacent ectodermal limb bud and breaks up to form intrinsic limb muscles (Figure 20.12). The splanchnic walls (i.e., those facing the yolk) of the two remaining pouches spread round the gut, forming the gut musculature, some fat body, and part of the reproductive system (Section 7.6). The somatic walls (those facing the ectoderm) of the anterior and posterior pouches give rise to extrinsic limb muscles, dorsal and ventral longitudinal muscles, and more fat body. For each muscle in an insect there is a single founder (pioneer) cell that serves as a base to which other progenitor muscle cells (myoblasts) become attached. As each muscle develops, it grows toward a specific epidermal insertion site (Chapter 14, Section 2.1).

The breaking up of the somite walls into discrete tissues means that in insects as in other arthropods there is no true coelom. Rather, the latter merges with the epineural sinus (the space between the dorsal surface of the embryo and the yolk) and is correctly

Beekeeping for Beginners

Beekeeping for Beginners

The information in this book is useful to anyone wanting to start beekeeping as a hobby or a business. It was written for beginners. Those who have never looked into beekeeping, may not understand the meaning of the terminology used by people in the industry. We have tried to overcome the problem by giving explanations. We want you to be able to use this book as a guide in to beekeeping.

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