Dorsal accessory olive

Fig. 158. Diagram of the inferior olive of the rat. A. Transverse sections 1-13 from caudal to rostral. B. Key to reconstruction of panel C. C. Flattened reconstruction of the inferior olive according to the method of Brodal (1940). Beta = subnucleus beta DAO = dorsal accessory olive DC = dorsal cap DLPO = dorsal leaf of the PO DM = dorsomedial group MAO= medial accessory olive PO = principal nucleus of the inferior olive VLO = ventrolateral outgrowth VLPO = ventral leaf of the PO. Ruigrok and Voogd (1990).

A dorsal and a ventral leaf usually are distinguished in the PO in the cat the ventral leaf is continuous with the medial pole of the dorsal accessory olive. In other mammals the DAO is continuous with the dorsal leaf and the ventral leaf ends as the DMCC in macaque monkeys and at the DM in rats. The ventral leaf of the PO caudally tapers into the ventrolateral outgrowth (VLO) that continues as the dorsal cap (DC) of Kooy (1917), located dorsal to the group beta. 

Fig. 164. The nucleo-olivary projection in the rat. Data from Ruigrok and Voogd (1990). Upper and lower block diagrams represent the cerebellar and vestibular nuclei, and the subdivisions of the inferior olive respectively. According to Ruigrok and Voogd (1990) the cerebellar nuclei and their olivary target nuclei can be considered as a continuum, stretching from the rostral medial cerebellar nucleus, projecting to caudal MAO, to the lateral vestibular nucleus, projecting to the dorsal fold of the DAO. DL = dorsolateral protuberance of the medial cerebellar nucleus DMC = dorsomedial cell column IntA = anterior interposed nucleus IntDL = dorsolateral hump IntP = posterior interposed nucleus lOD = dorsal accessory olive lODM = dorsomedial cell column lOM = medial accessory olive lOP = principal olive Lat = lateral cerebellar nucleus LVe = lateral vestibular nucleus Med = medial cerebellar nucleus VL = ventrolateral outgrowth.

Fig. 166. The innervation of the inferior olive of the rat by catecholaminergic, serotoninergic, substance P, and gamma-aminobutyric acid decarboxylase (GAD)-immunoreactive fibers and the distribution of acetylcholinesterase (AChE). a = subnucleus a of the medial accessory olive b = subnucleus b of the medial accessory olive beta = subnucleus beta DAO = dorsal accessory olive dc = dorsal cap dl = dorsal eaf principal olive DM = dorsomedial subnucleus dmcc = dorsomedial cell column MAO = medial accessory olive PO = principal olive vl = ventral leaf principal olive vlo = ventrolateral outgrowth XII = hypoglossal nerve.

Fig. 168. Schematic representation of the distribution of serotonin fibers in the inferior olivary complex of the cat (a, rostral i, caudal). B = group beta DA—DMC = dorsomedial cell column DAO = dorsal accessory olive DC = dorsal cap MAO = medial accessory olive PO = principal olive POD = dorsal lamella of the principal olive POV = ventral lamella of the principal olive. Takeuchi and Sano (1983).

Fig. 169. Diagram of the distribution of AChE in the inferior olive of the cat. A. Transverse sections, numbered from caudally to rostrally. B. Diagrams of the unfolded inferior olive. Black heavy staining stippled medium staining white low staining. Abbreviations DAO = dorsal accessory olive dc = dorsal cap dmcc = dor-somedial cell column MAO = medial accessory olive np = subnucleus beta PO = principal olive vio = ventrolateral outgrowth. Marani et al. (1977).

Fig. 173. A summary diagram of nociceptive and non-nociceptive cutaneous climbing fiber input to lobules IV and V of the cerebellum of the cat. Forked arrows show branching of olivary axons to innervate pairs of zones (Ekerot and Larson, 1982). PF, primary fissure DAO, dorsal accessory olive MAO, medial accessory olive. Garwicz (1992).

Fig. 178. Semidiagrammatic illustration showing the zonal arrangement in lobules IV and V of Saimiri based on projections from specific subnuclei of lO to each zone. A = A zone B = B zone C1.3 = ,.3 zones D,2 = D, 2 zones caudmao = caudal medial accessory olive dao ,, = medial/lateral part of the dorsal accessory olive ...

Fig. 179. Diagram of lamellar and zonal distribution of olivary afferents and efferents in the rat. The two lamellae (folds) of the dorsal accessory olive (DAO, 1 and 2) and the horizontal lamella of the medial accessory olive (MAO, 3) appear to receive afferents mainly from the spinal cord and dorsal column nuclei while projecting to anterior vermis and parts of intermediate cerebellum. The medial MAO (vertical lamella, 4) receives afferents from the vestibular and visual areas and projects to the posterior vermis as well as the flocculus. The rostral lamella of MAO and both lamellae of the principal olive (PO) receive projections from higher centers and send fibers to the lateral hemispheres. In the lower part of the figure, three drawings of the inferior olive demonstrate the lamellae corresponding to their sagittal zones of projection in the cerebellum. Azizi and Woodward (1987).

Fig. 185. The olivocerebellar projection to the pyramis and the uvula (lobules 8 and 9) of tbe rat cerebellum. A,B- Olivocerebellar projection zones of the lobules 8 and 9. C. Origin of these projections, indicated in diagrams of transverse sections through the inferior olive, a = subnucleus a of the medial accessory olive b = subnucleus b of the medial accessory olive beta = group beta c = subnucleus c of the medial accessory olive d = dorsal accessory olive dm = dorsomedial subnucleus m = medial accessory olive pr = principal olive 8 and 0 = lobules VIII and IX of Larsell. Relabelled and reproduced from Eisenman (1984).

Fig. 190. Distribution of CRF and CGRP-immunoreactive climbing fibers in P7 mouse cerebellum (A-C) and in neurons of the inferior olive (D-F). CRF-immunoreactive climbing fibers and neurons are indicated by dots, CGRP-immunoreactive climbing fibers and neurons by open circles, a, b and c = subnuclei a, b and c of the medial accessory olive beta -i- group beta Cl, C2 = Crus I and II DAO = dorsal accessory olive dc = dorsal cap EGL.ML = external granular layer and molecular layer F = flocculus IGL = internal granular layer PF = paraflocculus MAO = medial accessory olive PO = principal olive PL = Purkinje cell layer. Redrawn from Yamano and Tohyama (1993).

Molinari HH, Dostrosky JO, El-Yassir N (1990) Functional properties of dorsal horn neurons that project to the dorsal accessory olive. J. Neurophysiol, 64, 1704-1711. 

Wiklund L, Descarries L, Mollgard K (1981a) Serotoninergic axon terminals in the rat dorsal accessory olive normal ultrastructure and demonstration of regeneration after 5,6-dihydroxytryptamine lesioning. J. Ncuracy tol, 6, 1009-1027. 

---